1. Field of The Invention
The present invention relates to an ignition timing controlling apparatus and method for an internal combustion engine having an exhaust gas purification catalytic converter which achieve a promotion of activation of the exhaust gas purification catalytic converter maintaining a stability of engine driving.
It is necessary to activate an exhaust gas purification catalytic converter as early as possible after an engine has started, in order to improve an exhaust gas purification performance.
A Japanese Patent Application First Publication No. Heisei 5-272396 published on Oct. 19, 1993 exemplified a previously proposed engine control system in which an ignition timing is retarded after tile engine has started so that a gas component not combusted in the engine is exhausted to generate a recombustion heat within an exhaust passage, its reaction heat causing the exhaust gas purification catalytic converter to be activated as early as possible.
It is, however, noted that too large a retardation angle of the ignition timing causes an imperfect combustion per se so that a surge and/or revolution speed variation is generated. This means a worsening in engine driveability. A limit is placed on the remarkable retardation of the ignition timing angle.